Ms. Danko, whose last day was Thursday, will be vice president of public affairs for the Securities Industry and Financial Markets Association in Washington, D.C.

Ms. Danko has been Grimm's only spokeswoman since he went to the House in 2011. She was also Grimm's policy adviser on Hurricane Sandy.

She called the past three years of service "unforgettable."

"It was a sincere pleasure serving the people of Staten Island and Brooklyn, and I am honored to have met so many remarkable people in the district," she said, "particularly those impacted by Sandy and the members of the community who came to their aid and continue to help rebuild."

Ms. Danko went to work for Grimm after spending five years on the staff of Rep. Peter King (R-L.I.). She also worked for Rep. Tom Price (R-Ga.).

"We are losing a good part of the team in Carol Danko," Grimm said. "She is a consummate professional."

He lauded the work she did during Sandy, saying Ms. Danko was a force on the ground and often worked around the clock.

"She really stepped up to the plate during Sandy," he said. "Her dedication to the people of Staten Island and Brooklyn is beyond appreciated, and will be sorely missed."

While sad to see her go, Grimm said he was excited to see Ms. Danko move on to her new position.

"I'm really proud and excited for her," he said. "She is going to have a tremendously successful career."

Grimm said his office was in search of a replacement for Ms. Danko.

Grimm's District Director Nick Curran will handle Sandy-related matters. Press inquiries will be handled by Nick Iacono until a replacement for Ms. Danko is found.